Climate Change and Impact on Stormwater Systems – Can We Change Our Future?

We face an uncertain future as a changing climate starts to expose our historical land use decisions. The Intergovernmental Panel on Climate Change identified key climate risks to New Zealand being continuing sea level rise and the increased frequency and intensity of flood damage on our low-lying and coastal infrastructure (IPCC, 2014).

White et al, (2017) identify that “Stormwater and wastewater systems are particularly vulnerable to climate change as the discharge points of these systems are often at the lowest elevation of populated areas. Even small changes in rainfall extremes, including intensity and duration, can overwhelm the design capacity of these systems. In low-lying areas where groundwater is linked to the sea, sea level rise will affect the performance of stormwater systems and wastewater systems where infiltration occurs.

Droughts will also affect the performance and maintenance of wastewater systems. Increased urbanization associated with new greenfield housing, and densification in existing areas will also challenge existing design parameters. Furthermore, some of the stormwater and wastewater systems most exposed to climate change hazards are aging. Funding any replacement is already challenging in some areas, where there are declining rate bases due to population shifts towards urban centres, combined with caps on local government lending. However, as systems are replaced there is an opportunity to redesign for resilience.”

This paper will focus on communicating the outputs from a recently completed Deep South Challenge Dialogue on Climate Change impacts on stormwater and wastewater systems across New Zealand (White et al., 2017). With over $50 billion of our built assets and approx. 6.6% of our population located within a ‘particularly exposed’ area (Bell et al., 2016), New Zealand is at a cross roads, with ‘tough decisions’ being required to help us adapt our communities, our critical infrastructure and our overall way of life to the forthcoming challenge.

Selwyn District Council (2017) identifies that climate change effects on three waters infrastructure systems are harder to distinguish compared with inter-decadal climatic patterns. The paper will share the lessons learnt from this research, which would include changing our messaging such that we are not to be solely focused on communicating ‘future’ risk, but equally and more relevant to land use planning, the risks we have overcome to date and the ones we face cyclically.

The paper showcases some examples of the transformational changes from our historic land use approaches through to those that will be required for us to better adapt our rural and urban environments now and into the future. This way we can seek to deliver increased resilience, better outcomes and places that people want to live and work in.

The paper will identify how communities around New Zealand are starting to ‘plan’ for adaptation as a means for resolving current and future issues, drawing examples from across the spectrum of Local Government entities, such as Christchurch and Gisborne.